1. Field of Use
This invention relates generally to vehicle seats such as are used as driver's or operator's seats on vehicles such as farm tractors, construction machines, or the like. In particular, it relates to vehicle seats wherein the backrest assembly includes adjustable lumbar support means.
2. Description of the Prior Art
Some vehicle seats comprise a seat assembly and an attached backrest assembly and are constructed so as to be mountable either on the floor or on a floor-mounted pedestal in the driver's compartment or station on the vehicle. In some vehicle seats, the backrest assembly includes or is provided with a lumbar support which imparts a curvature to the upholstered front portion of the backrest assembly to thereby provide a supporting contour for the lumbar region of the seat occupant. U.S. Pat. No. 3,948,558 and 3,973,797 disclose lumbar supports which can be adjustably moved forward or rearward by means of an externally accessible adjustment level. In both of these patents, the lumbar support is so constructed and mounted on the backrest assembly that no substantial relative vertical movement is possible, i.e., if the height of the backrest is changed, the height of the lumbar support changes accordingly.